The present invention relates to optical analysis systems and methods for analyzing fluids and, in particular, to systems and methods for monitoring chemical reaction processes in or near real-time.
In the oil and gas industry, it is often important to precisely know the characteristics and chemical composition of fluids as they circulate into and out of subterranean formations, vessels, and pipelines. Typically, oil and gas fluid analyses have been conducted off-line using laboratory analyses, such as spectroscopic and/or wet chemical methods, which analyze an extracted sample of the fluid. Depending on the analysis required, however, such an approach can take hours to days to complete, and even in the best case scenario, a job will often be completed prior to the analysis being obtained. Furthermore, off-line laboratory analyses can sometimes be difficult to perform, require extensive sample preparation and present hazards to personnel performing the analyses. Bacterial analyses, for example, can particularly take a long time to complete since culturing of a bacterial sample is usually needed to obtain satisfactory results.
Although off-line, retrospective analyses can be satisfactory in certain cases, but they do not provide real-time or near real-time analysis capabilities. As a result, proactive control of a subterranean operation or fluid flow within related vessels or pipelines cannot take place, at least without significant process disruption occurring while awaiting the results of the analysis. Off-line, retrospective analyses can also be unsatisfactory for determining true characteristics of a fluid since the characteristics of the extracted sample of the fluid oftentimes change during the lag time between collection and analysis, thereby making the properties of the sample non-indicative of the true chemical composition or characteristic. For example, factors that can alter the characteristics of a fluid during the lag time between collection and analysis can include, scaling, reaction of various components in the fluid with one another, reaction of various components in the fluid with components of the surrounding environment, simple chemical degradation, and bacterial growth.
Monitoring fluids in or near real-time can be of considerable interest in order to monitor chemical reaction processes, thereby serving as a quality control measure for processes in which fluids are used. Specifically, there are many chemical processes which require physical and chemical parameters to be altered based on the concentration of reactants in the process or products produced by the process. For example, temperatures, pressures, flow rates, pH and other physical parameters of the process must frequently be monitored and changed to optimize the progress of the chemical process.
Spectroscopic techniques for measuring chemical reaction processes are well known and are routinely used under laboratory conditions. In some cases, these spectroscopic techniques can be carried out without using an involved sample preparation. It is more common, however, to carry out various sample preparation procedures before conducting the analysis. Reasons for conducting sample preparation procedures can include, for example, removing interfering background materials from the analyte of interest, converting the analyte of interest into a chemical form that can be better detected by a chosen spectroscopic technique, and adding standards to improve the accuracy of quantitative measurements. Thus, there is usually a delay in obtaining an analysis due to sample preparation time, even discounting the transit time of transporting the extracted sample to a laboratory.
Although spectroscopic techniques can, at least in principle, be conducted at a job site, such as a well site, or in a process, the foregoing concerns regarding sample preparation times may still apply. Furthermore, the transitioning of spectroscopic instruments from a laboratory into a field or process environment can be expensive and complex. Reasons for these issues can include, for example, the need to overcome inconsistent temperature, humidity, and vibration encountered during field use. Furthermore, sample preparation, when required, can be difficult under field analysis conditions. The difficulty of performing sample preparation in the field can be especially problematic in the presence of interfering materials, which can further complicate conventional spectroscopic analyses. Quantitative spectroscopic measurements can be particularly challenging in both field and laboratory settings due to the need for precision and accuracy in sample preparation and spectral interpretation.